The proposed project is an attempt to investigate one of the factors responsible for cardiovascular diseases. In certain heritable and induced diseases of the aorta and the connective tissues in general, the enzyme lysyl oxidase is evidently lacking or is present in low concentrations and cross links in the protocollagen and proelastin which are required to form mature elastin and collagen are not formed. Since very little is known about this enzyme lysyl oxidase, we propose to purify the bovine aorta enzyme to a homogeneous state. The enzyme in our preliminary studies has already been 1,000 fold purified. The enzyme will be completely characterized by methods which we have already published (we have already published about 28 papers on different kinds of amine oxidases). This includes physicochemical investigations, mechanistic studies, essential amino acid residues present, determination of the cofactors of the enzyme, studies on substrate and inhibitor specificity of the enzyme, and a development of a simple procedure for assaying the amount of enzyme in different tissues. This latter procedure may make it possible to assay the enzyme in different diseased states. The action of the purified enzyme on proelastin, protocollagen and simple lysine peptides will be investigated. Proelastin and protocollagen can be obtained from experimental animals grown under a copper-deficient diet. Some sequence investigations of the proelastin will be undertaken of a preliminary nature. (We have sequenced 15 proteins to date and the methods are discussed in these publications). Thus the proposed project has relevance to cardiovascular diseases as well as diseases of the connective tissue and the aging problem.